CN111162756B

CN111162756B - Multiplexer

Info

Publication number: CN111162756B
Application number: CN201911064872.3A
Authority: CN
Inventors: 向井孝雄
Original assignee: Murata Manufacturing Co Ltd
Current assignee: Murata Manufacturing Co Ltd
Priority date: 2018-11-08
Filing date: 2019-11-01
Publication date: 2023-09-08
Anticipated expiration: 2039-11-01
Also published as: CN111162756A; KR20200053404A; US10979029B2; KR102546485B1; KR20210031881A; KR102312071B1; US20200153411A1; JP7151668B2; JP2020078048A

Abstract

A multiplexer having a plurality of elastic wave filters, which reduces the generation of IMD and has excellent passing characteristics. The multiplexer (1) is provided with a filter (22) arranged on the 1 st path, a filter (12) arranged on the 2 nd path, and a filter (21) arranged on the 3 rd path, and the frequency of intermodulation distortion IMD generated by a transmission signal (B1 Tx) in the passband of the filter (22) and a transmission signal (B3 Tx) in the passband of the filter (12) is contained in the passband of the filter (21). The filter (22) has one or more series-arm resonant circuits arranged on the 1 st path and one or more parallel-arm resonant circuits arranged on the path connecting the corresponding node on the 1 st path to the ground, and at least one resonant circuit among the one or more series-arm resonant circuits and the resonant circuit closest to the common terminal (Port 1) among the one or more parallel-arm resonant circuits is composed of a divided resonator group composed of a plurality of divided resonators connected in series with each other.

Description

Multiplexer

Technical Field

The present invention relates to multiplexers.

Background

In recent years, in order to perform communication corresponding to a plurality of frequency bands (multiple frequency bands) and a plurality of wireless systems (multiple modes) with one terminal, for example, a quad-type device in which two diplexers each including a transmission filter and a reception filter each including an elastic wave resonator are connected to a common terminal has been proposed (for example, patent document 1).

Prior art literature

Patent literature

Patent document 1: international publication No. 2018/003297

However, in a multiplexer such as a quad multiplexer configured by using an elastic wave filter as in patent document 1, intermodulation distortion (IMD: intermodulation Distortion) is likely to occur due to the nonlinear characteristics of the elastic wave filter itself.

In particular, in a multiplexer applied to CA (Carrier Aggregation ) that performs communication using a plurality of frequency bands simultaneously, IMD having a frequency equal to that of a received signal may be generated from transmission signals of two different frequency bands. Such IMDs are generated by interference between transmission signals, and therefore have high signal strength, and the pass characteristics of the multiplexer are easily degraded.

Disclosure of Invention

Problems to be solved by the invention

In view of the above problems, an object of the present invention is to provide a multiplexer having a plurality of elastic wave filters, which reduces the generation of IMDs and has excellent passing characteristics.

Means for solving the problems

In order to achieve the above object, a multiplexer according to an embodiment of the present invention includes: a1 st transmission filter disposed on a1 st path connecting the common terminal and the 1 st terminal; a2 nd transmission filter disposed on a2 nd path connecting the common terminal and the 2 nd terminal; and a reception filter disposed on a3 rd path connecting the common terminal and the 3 rd terminal, the frequency of intermodulation distortion being included in a passband of the reception filter, the intermodulation distortion being generated by a1 st transmission signal whose frequency is included in the passband of the 1 st transmission filter and a2 nd transmission signal whose frequency is included in the passband of the 2 nd transmission filter, the 1 st transmission filter having: more than one series arm resonant circuit arranged on the 1 st path; and one or more parallel-arm resonant circuits arranged on a path connecting a corresponding node on the 1 st path to ground, wherein at least one of the one or more series-arm resonant circuits of the 1 st transmission filter and a resonant circuit closest to the common terminal among the one or more parallel-arm resonant circuits is composed of a divided resonator group composed of a plurality of divided resonators connected in series with each other.

Further, another multiplexer according to an embodiment of the present invention includes: a1 st transmission filter disposed on a1 st path connecting the common terminal and the 1 st terminal; a2 nd transmission filter disposed on a2 nd path connecting the common terminal and the 2 nd terminal; and a reception filter disposed on a3 rd path connecting the common terminal and the 3 rd terminal, the frequency of intermodulation distortion being included in a passband of the reception filter, the intermodulation distortion being generated by a1 st transmission signal whose frequency is included in the passband of the 1 st transmission filter and a2 nd transmission signal whose frequency is included in the passband of the 2 nd transmission filter, the 1 st transmission filter having: more than one series arm resonant circuit arranged on the 1 st path; and one or more parallel-arm resonant circuits disposed on a path connecting a corresponding node on the 1 st path and ground, wherein each of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 1 st transmission filter is configured by an elastic wave resonator having IDT (Inter Digital Transducer ) electrodes, and a duty ratio of an IDT electrode of at least one of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits closest to the common terminal is smaller than that of IDT electrodes of other arbitrary resonant circuits of the 1 st transmission filter.

Effects of the invention

According to such a configuration, at least one of the resonance circuits closest to the common terminal, that is, the resonance circuit in which IMD is most likely to occur due to the most easy concentration of the power of the signal, among the resonance circuits constituting the 1 st transmission filter is constituted by the divided resonator group, or by the resonance circuit in which the duty ratio of the IDT electrode is smaller than that of the IDT electrode of the other resonance circuit.

Accordingly, the area occupied by the resonant circuit in the piezoelectric substrate increases, and the power consumption per unit area decreases, so that IMD generated by the resonant circuit is reduced. Since the resonance circuit in which the power of the signal is most likely to be concentrated is divided, the effect of reducing the IMD can be maximized against the disadvantage of the large-scale resonance circuit.

Drawings

Fig. 1 is a block diagram showing an example of a functional configuration of a basic multiplexer.

Fig. 2 is a diagram showing an example of pass bands of filters constituting a multiplexer.

Fig. 3 is a circuit diagram showing an example of the basic configuration of the filter.

Fig. 4 is a schematic diagram showing an example of a basic structure of an acoustic wave resonator.

Fig. 5A is a schematic diagram showing an example of an IMD generated in a multiplexer.

Fig. 5B is a schematic diagram showing an example of an IMD generated in a multiplexer.

Fig. 6 is a circuit diagram showing an example of the structure of the filter according to the embodiment.

Fig. 7 is a circuit diagram showing another example of the structure of the filter according to the embodiment.

Fig. 8 is a graph showing an example of calculation of the intensity of the IMD according to the embodiment.

Description of the reference numerals

1. 1a, 1b quadruplex;

2. 2a, 2b antenna elements;

10. a 20 duplexer;

11. a filter;

12. a filter (transmission filter 2);

21. a filter (reception filter);

22. 22a, 22b filters (1 st transmission filter);

30. an elastic wave resonator;

30a, 30b comb-like electrodes;

31a, 31b electrode fingers;

32a, 32b bus bar electrodes;

33 An IDT electrode;

34. a protective layer;

39. a piezoelectric layer;

111. 111a, 111b, 112 to 114;

111a1 to 111a4, 121a1 to 121a3 divide the resonators;

121. 121a, 121b, 122 to 124.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the embodiments and drawings. The embodiments described below each show a general or specific example. The numerical values, shapes, materials, components, arrangement of components, connection modes, and the like shown in the following embodiments are examples, and the gist of the present invention is not limited thereto. In the following embodiments, the term "connection" includes not only a case where the connection is made directly by a wiring conductor but also a case where the connection is made electrically via another circuit element.

(embodiment)

The multiplexer according to the embodiment will be described with reference to an example of a quad multiplexer.

Fig. 1 is a block diagram showing an example of a functional configuration of a basic quad stage applied to an embodiment. In addition, in fig. 1, an antenna element 2 connected to a common terminal Port1 of the quad 1 is also illustrated.

As an example, the quad 1 passes a high-frequency signal of Band described later, which is defined by 3GPP (registered trademark) (Third Generation Partnership Project ), in accordance with LTE (registered trademark) (Long Term Evolution ).

As shown in fig. 1, the quad 1 has a common terminal Port1, four independent terminals Port11, port12, port21 and Port22, and four filters 11, 12, 21 and 22.

The common terminal Port1 is provided commonly to the four filters 11, 12, 21, and 22, and is connected to the filters 11, 12, 21, and 22 inside the quad 1. The common terminal Port1 is connected to the antenna element 2 outside the quad 1. That is, the common terminal Port1 is also an antenna terminal of the quad 1.

The individual terminals Port11, port12, port21, and Port22 are provided corresponding to the filters 11, 12, 21, and 22, respectively, and are connected to the corresponding filters inside the quad 1. The individual terminals Port11, port12, port21, and Port22 are connected to an RF signal processing circuit (RFIC: radio Frequency Integrated Circuit, radio frequency integrated circuit, not shown) via an amplifier circuit or the like (not shown) outside the quad 1.

The filter 11 is a reception filter which is disposed on a path connecting the common terminal Port1 and the independent terminal Port11 and has a passband of the downlink Band in Band 3.

The filter 12 is a transmission filter which is disposed on a path connecting the common terminal Port1 and the independent terminal Port12 and has a passband of an uplink Band in Band 3.

The filter 21 is a reception filter which is disposed on a path connecting the common terminal Port1 and the independent terminal Port21 and has a passband of a downlink Band in Band 1.

The filter 22 is a transmission filter which is disposed on a path connecting the common terminal Port1 and the independent terminal Port22 and has a passband of an uplink Band in Band 1.

Here, the independent terminal Port22 is an example of the 1 st terminal, and the filter 22 is an example of a1 st transmission filter arranged on the 1 st path connecting the common terminal Port1 and the independent terminal Port22 as the 1 st terminal.

The independent terminal Port12 is an example of the 2 nd terminal, and the filter 12 is an example of a2 nd transmission filter arranged on the 2 nd path connecting the common terminal Port1 and the independent terminal Port12 as the 2 nd terminal.

The independent terminal Port21 is an example of the 3 rd terminal, and the filter 21 is an example of a reception filter disposed on the 3 rd path connecting the common terminal Port1 and the independent terminal Port21 as the 3 rd terminal.

The filters 11 and 12 constitute a duplexer 10 for dividing and combining the transmission signal and the reception signal of Band 3. The filters 21 and 22 constitute a duplexer 20 for dividing and combining the transmission signal and the reception signal of Band 1.

As described above, the quad 1 is configured by connecting the common terminal of the duplexer 10 for Band3 and the common terminal of the duplexer 20 for Band1 to each other at the node N, and further, by connecting the common terminal Port 1.

In the quad 1, an impedance element such as an inductor for impedance matching may be connected to a path connecting the filters 11, 12, 21, and 22 and the node N, a path connecting the node N and the common terminal Port1, or the like.

Here, specific ranges of the bands allocated to Band1 and Band3, which are pass bands of the quad 1, will be described. Hereinafter, the numerical ranges indicating a or more and B or less are abbreviated as a to B with respect to the range of the frequency band.

Fig. 2 is a diagram illustrating the frequency bands allocated to Band1 and Band 3. In addition, hereinafter, the downlink Band (reception Band) and the uplink Band (transmission Band) of each Band may be described in a simplified manner by a Band name and a character Rx or Tx indicating the reception Band or the transmission Band attached to the end thereof, for example, in a simplified manner as "Band1Rx" with respect to the reception Band of Band 1.

As shown in fig. 2, with respect to Band1, 1920 to 1980MHz are allocated to the transmission Band1Tx, and 2110 to 2170MHz are allocated to the reception Band1Rx. With respect to Band3, 1710 to 1785MHz is allocated to the transmission Band3Tx, and 1805 to 1880MHz is allocated to the reception Band3 Rx. Therefore, as the filter characteristics of the filters 11, 12, 21, and 22, characteristics are required such that the transmission Band or the reception Band of the corresponding Band passes and the other Band is attenuated as shown by the solid line in fig. 2.

Next, the basic configuration of each of the filters 11, 12, 21, and 22 will be described by taking the filter 22 (the 1 st transmission filter) having the Band1Tx as a passband as an example. The structure of the filter described below may be applied not only to the filter 22 but also to the filters 11, 12, and 21.

Fig. 3 is a circuit diagram showing an example of the basic configuration of the filter 22. As shown in fig. 3, the filter 22 includes series-arm resonant circuits 111 to 114 and parallel-arm resonant circuits 121 to 124. The series-arm resonant circuits 111 to 114 and the parallel-arm resonant circuits 121 to 124 are each constituted by, for example, a surface acoustic wave (SAW: surface Acoustic Wave) resonator, that is, an acoustic wave resonator having IDT electrodes.

The series arm resonant circuits 111 to 114 are connected in series to each other in order from the common terminal Port1 side on a path (series arm) connecting the common terminal Port1 and the individual terminal Port 22. The parallel arm resonant circuits 121 to 124 are connected in parallel to each other on a path (parallel arm) connecting the corresponding connection points of the series arm resonant circuits 111 to 114 and the reference terminal (ground). Thus, the filter 22 constitutes a bandpass filter having a 4-stage ladder configuration.

The number of the series-arm resonant circuits and the parallel-arm resonant circuits included in the filter 22 is not limited to 4, and may be one or more of the series-arm resonant circuits and one or more of the parallel-arm resonant circuits. That is, the filter 22 may be a filter having a ladder structure of 1 stage or more.

The parallel arm resonant circuits 121 to 124 may be connected to a reference terminal (ground terminal) via an inductor (not shown). Further, impedance elements such as an inductor and a capacitor may be inserted or connected to the series arm, the parallel arm, or both.

Further, the parallel-arm resonant circuit may be connected to a node on the common terminal Port1 side of the series-arm resonant circuit 111 closest to the common terminal Port1 among the series-arm resonant circuits 111 to 114 constituting the ladder-type filter structure. The parallel-arm resonant circuit 124 connected to the node on the independent terminal Port22 side of the series-arm resonant circuit 114 closest to the independent terminal Port22 may be omitted.

Next, a basic structure of an elastic wave resonator used in a resonant circuit constituting the filter 22 will be described.

Fig. 4 is a schematic diagram showing an example of a basic structure of an acoustic wave resonator, where (a) is a plan view and (b) is a side view. Fig. 4 (b) corresponds to a cross section at a one-dot chain line shown in fig. 4 (a). The structure of the acoustic wave resonator 30 shown in fig. 4 is also applicable to, for example, acoustic wave resonators included in any of the series-arm resonant circuits 111 to 114 and the parallel-arm resonant circuits 121 to 124 constituting the filter 22, and the resonant circuits constituting the filters 11, 12, and 21. The illustration of fig. 4 is used to explain the basic structure of the acoustic wave resonator, and the number and length of electrode fingers constituting the electrode are not limited to this.

The acoustic wave resonator 30 is formed by forming IDT electrodes 33 on a piezoelectric layer 39 and covering them with a protective layer 34. As an example, the piezoelectric layer 39 may be made of a piezoelectric material containing lithium tantalate, lithium niobate, or the like, and the IDT electrode 33 may be made of a metal such as copper, aluminum, or the like, or an alloy thereof. The protective layer 34 may be made of a protective material containing silicon dioxide or the like as a main component. The piezoelectric layer 39 may be formed on a support substrate made of a silicon substrate or the like, or the piezoelectric layer 39 itself may be a support substrate.

The IDT electrode 33 is composed of 1 pair of comb-shaped electrodes 30a and 30b facing each other. The comb-shaped electrode 30a is composed of a plurality of electrode fingers 31a parallel to each other and bus bar electrodes 32a connecting the plurality of electrode fingers 31 a. The comb-shaped electrode 30b is composed of a plurality of electrode fingers 31b parallel to each other and bus bar electrodes 32b connecting the plurality of electrode fingers 31 b. The electrode fingers 31a and 31b are formed along a direction orthogonal to the X-axis direction. The elastic wave excited by the IDT electrode 33 propagates in the X-axis direction in the piezoelectric layer 39.

The parameter defining the shape and size of the IDT electrode 33 is referred to as an electrode parameter. As an example of the electrode parameters, there may be mentioned: a wavelength λ which is a repetition period of the electrode finger 31a or the electrode finger 31b in the propagation direction of the elastic wave, a crossing width L which is a length of repetition of the electrode fingers 31a, 31b when viewed in the propagation direction of the elastic wave, a line width W of the electrode fingers 31a, 31b, and a space width S between adjacent electrode fingers 31a, 31 b.

The logarithm N of 1/2 of the number of electrode fingers that hold the electrode fingers 31a, 31b together, the electrode pitch (w+s) that is the repetition period of the electrode fingers that hold the electrode fingers 31a, 31b together, and the duty ratio W/(w+s) that is the ratio of the line width W to the electrode pitch are also examples of the electrode parameters.

Next, the IMD generated in the multiplexer will be described with reference to the configuration of the quad 1 of fig. 1 and the example of the frequency band of fig. 2.

Fig. 5A shows an example of IMD generated in the quad 1 in the case where the transmission signal B1Tx of Band1 and the transmission signal B3Tx of Band3 are simultaneously transmitted from one antenna element 2 via the quad 1.

Fig. 5B shows an example of IMDs generated in the quadplexers 1a, 1B in the case where the transmission signal of Band1 and the transmission signal of Band3 are simultaneously transmitted from the two antenna elements 2a, 2B via the quadplexers 1a, 1B, respectively. The quadplexers 1a and 1b each have the same structure as the quadplexer 1.

In either fig. 5A and 5B, the transmission signals B1Tx and B3Tx of the intensity of the degree of actual transmission are concentrated directly or via the coupling between the antenna elements 2a and 2B on the circuit parts C, ca and Cb (shown by hatching) of the quadplexers 1, 1a and 1B. Therefore, IMDs transmitting signals B1Tx, B3Tx are easily generated in the circuit parts C, ca, cb.

For example, from the frequency f of the transmission signal B1Tx _B1Tx Is reduced by 2 times the frequency f of the transmission signal B3Tx _B3Tx And the obtained frequency 2f _B1Tx -f _B3Tx Frequency f of reception signal B1Rx with Band1 _B1Rx And (5) repeating. When IMD included in Band1Rx is generated from the transmission signals B1Tx and B3Tx, the reception signal B1Rx is blocked by the generated IMD, and the reception sensitivity in Band1 is deteriorated.

The nonlinear element that easily generates IMD in the circuit parts C, ca, cb is, for example, an elastic wave resonator included in a resonance circuit closest to the common terminal Port1 among resonance circuits constituting the filter 22. In the example of fig. 3, among the series-arm resonant circuits 111 to 114 and the parallel-arm resonant circuits 121 to 124 constituting the filter 22, the series-arm resonant circuit 111 and the parallel-arm resonant circuit 121 are the resonant circuits closest to the common terminal Port1 because they are directly connected to the common terminal Port 1.

The resonance circuit closest to the common terminal Port1 easily concentrates the power of a plurality of signals (for example, the power of the transmission signals B1Tx, B3 Tx). Accordingly, a large power such as to generate a nonlinear response is concentrated on the elastic wave resonator included in the resonance circuit, thereby generating the IMD.

Therefore, in the embodiment, the elastic wave resonator included in the resonant circuit closest to the common terminal Port1 in the filter 22 is configured such that the consumed power per unit area (hereinafter, simply referred to as consumed power) occupied by the piezoelectric substrate is less likely to be increased than the elastic wave resonator included in the other resonant circuit. In the case where there are a plurality of resonance circuits closest to the common terminal Port1 (for example, the series-arm resonance circuit 111 and the parallel-arm resonance circuit 121 in fig. 3), a structure is employed in which the power consumption is less likely to be increased for the elastic wave resonator included in at least one (or all) of the resonance circuits closest to the common terminal Port 1.

Fig. 6 is a circuit diagram showing an example of the structure of the filter according to the embodiment. As shown in fig. 6, the filter 22a differs from the filter 22 of fig. 3 in that the series-arm resonant circuit 111a and the parallel-arm resonant circuit 121a (shown in bold line) are each composed of a divided resonator group.

The split resonator group is a resonant circuit composed of a plurality of acoustic wave resonators connected in series, and is defined as a structure in which circuit elements other than the plurality of acoustic wave resonators are not connected to a connection node connecting the plurality of acoustic wave resonators and are grounded.

The series-arm resonant circuit 111a is constituted by a divided resonator group constituted by a plurality of divided resonators 111a1, 111a2, 111a3, and 111a4 connected in series with each other. The parallel arm resonant circuit 121a is constituted by a divided resonator group constituted by a plurality of divided resonators 121a1, 121a2, and 121a3 connected in series with each other. The split resonators 111a1 to 111a4 and 121a1 to 121a3 are also elastic wave resonators each having IDT electrodes, and have a structure shown in fig. 4, for example.

In general, in a divided resonator group composed of a plurality of divided resonators connected in series with each other, in order to obtain the same capacitance as that of a single elastic wave resonator, an elastic wave resonator having a capacitance larger than that of the single elastic wave resonator is used for each divided resonator. Therefore, the area occupied by the resonant circuit in the piezoelectric substrate is increased and the power consumption per unit area is reduced, compared with the resonant circuit having the same capacitance and formed of a single elastic wave resonator, in the resonant circuit formed of the divided resonator group, and therefore, the IMD generated by the resonant circuit is reduced.

In the example of the filter 22a, the series-arm resonant circuit 111a and the parallel-arm resonant circuit 121a each composed of a divided resonator group have a larger area occupied by the piezoelectric substrate and a smaller power consumption per unit area than the series-arm resonant circuit 111 and the parallel-arm resonant circuit 121 each composed of a single elastic wave resonator, and therefore the IMD is reduced. Further, since the series-arm resonant circuit 111a and the parallel-arm resonant circuit 121a closest to the common terminal Port1 and thus where the power of the signal is most likely to be concentrated are constituted by the divided resonator group, the effect of reducing the IMD can be maximized with respect to the disadvantage of the large-sized resonant circuit.

Fig. 7 is a circuit diagram showing another example of the structure of the filter according to the embodiment. As shown in fig. 7, the filter 22b is different from the filter 22 of fig. 3 in that the duty ratio of IDT electrodes of the series-arm resonant circuit 111b and the parallel-arm resonant circuit 121b (shown in bold line) is smaller than the duty ratio of IDT electrodes of the series-arm resonant circuit 111 and the parallel-arm resonant circuit 121, respectively.

In general, when the duty ratio of the IDT electrode is reduced, the resonance characteristic of the elastic wave resonator shifts to the high frequency side. Such variations in resonance characteristics can be offset by enlarging the repetition period of the electrode fingers, for example, when the number of pairs and the cross width of IDT electrodes are fixed. Therefore, in the elastic wave resonator in which the duty ratio of the IDT electrode is reduced and the repetition period of the electrode finger is increased to cancel out the fluctuation of the resonance characteristic, the area occupied by the elastic wave resonator on the piezoelectric substrate is increased, and the power consumption per unit area is reduced, so that the IMD generated by the elastic wave resonator is reduced.

In the example of the filter 22b, the duty ratio of the IDT electrode of the series-arm resonant circuit 111b and the parallel-arm resonant circuit 121b is smaller than the duty ratio of the IDT electrode of the other resonant circuit. According to the series-arm resonant circuit 111b and the parallel-arm resonant circuit 121b, the area occupied by the piezoelectric substrate is larger than that of other resonant circuits having larger duty ratios of IDT electrodes, and thus the power consumption per unit area is reduced, and hence the IMD is reduced. Further, since the duty ratios of IDT electrodes of the series-arm resonant circuit 111b and the parallel-arm resonant circuit 121b closest to the common terminal Port1 and thus where the power of the signal is most likely to be concentrated are made smaller, the effect of reducing the IMD can be maximized with respect to the disadvantage of the larger size of the resonant circuit.

In the above description, the filter 22 has been described with an example (filter 22 a) in which at least one of the resonator circuits closest to the common terminal Port1 is formed by dividing the resonator group, and an example (filter 22 b) in which the duty ratio of the IDT electrode is smaller than that of the IDT electrode of the other resonator circuit. The same structure is not limited to the filter 22, and may be applied to the filter 12, and may be applied to both the filters 22 and 12.

Next, the effect of IMD reduction in the case where the filters 22a and 22b are used in place of the filter 22 in the quad filter 1 will be described based on the simulation result.

In the simulation, IMDs in the quad 1 (fig. 5A) using the filter 22 (fig. 3) and the quad (not shown) in which the filter 22 of the quad 1 was replaced with the filter 22a (fig. 6) and the filter 22b (fig. 7) were compared. Hereinafter, a quad-stage device using filters 22, 22a, and 22b will be referred to as comparative example, example 1, and example 2, respectively.

Table 1 shows electrode parameters set for the acoustic wave resonators included in the series-arm resonant circuits 111, 111a, and 111b and the acoustic wave resonators included in the parallel-arm resonant circuits 121, 121a, and 121b in the comparative example, the example 1, and the example 2. The number of split resonators included in the split resonator group is shown as the number of splits, and the electrode parameters set for each split resonator are shown for the series-arm resonant circuit 111a and the parallel-arm resonant circuit 121a that are each composed of the split resonator group. In example 1 and example 2, the electrode parameters emphasized by the shading were changed from the comparative examples.

TABLE 1

The electrode parameters of the acoustic wave resonators included in each of the series-arm resonant circuits 112 to 114 and the parallel-arm resonant circuits 122 to 124, which are not shown in table 1, are the same in comparative examples, example 1, and example 2. In particular, the duty ratios and the division numbers of the acoustic wave resonators included in the series-arm resonant circuits 112 to 114 and the parallel-arm resonant circuits 122 to 124 are all set to 0.5 and1 in the comparative example, the example 1, and the example 2, respectively. Here, the elastic wave resonator having a division number of 1 means a single elastic wave resonator that is not divided.

As described above, in embodiment 1, the series-arm resonant circuit 111a and the parallel-arm resonant circuit 121a among the resonant circuits constituting the filter 22a are constituted by divided resonator groups. In embodiment 2, the duty ratio of IDT electrodes of the series-arm resonant circuit 111b and the parallel-arm resonant circuit 121b among the resonant circuits constituting the filter 22b is smaller than that of IDT electrodes of other resonators.

Regarding comparative example, example 1 and example 2, the intensity of IMD in the reception Band (2110 to 2170 MHz) of Band1 at the independent terminal Port21 was calculated. In the calculation of the intensity of IMD, assuming that the quadruplex 1a in the configuration of fig. 5B is applied, the signal intensities of the transmission signals of Band1 and Band3 at the output ends of the filter 22 and the filter 12 are set to 25dBm and 10dBm, respectively.

Fig. 8 is a graph showing an example of calculation of the intensity of the IMD. As can be seen from fig. 8, the intensity of the IMD in example 1 is in the entire range of the reception Band of Band1, and the intensity of the IMD in example 2 is in most of the reception Band of Band1, and is reduced (improved) compared with the intensity of the IMD in the comparative example.

From this result, it was confirmed that it is effective for the reduction of IMD to construct a resonant circuit closest to the common terminal and easily generating IMD due to the easy concentration of the power of the signal by the divided resonator group, or to make the duty ratio of IDT electrode of this resonant circuit smaller than that of IDT electrode of other resonant circuit.

(summary)

The multiplexer according to one embodiment of the present invention includes: a1 st transmission filter disposed on a1 st path connecting the common terminal and the 1 st terminal; a2 nd transmission filter disposed on a2 nd path connecting the common terminal and the 2 nd terminal; and a reception filter disposed on a3 rd path connecting the common terminal and the 3 rd terminal, the frequency of intermodulation distortion being included in a passband of the reception filter, the intermodulation distortion being generated by a1 st transmission signal whose frequency is included in the passband of the 1 st transmission filter and a2 nd transmission signal whose frequency is included in the passband of the 2 nd transmission filter, the 1 st transmission filter having: more than one series arm resonant circuit arranged on the 1 st path; and one or more parallel-arm resonant circuits arranged on a path connecting a corresponding node on the 1 st path to ground, wherein at least one of the one or more series-arm resonant circuits of the 1 st transmission filter and a resonant circuit closest to the common terminal among the one or more parallel-arm resonant circuits is composed of a divided resonator group composed of a plurality of divided resonators connected in series with each other.

According to this configuration, at least one of the resonance circuits closest to the common terminal in the 1 st transmission filter, that is, the resonance circuit in which IMD is easily generated due to easy concentration of power of the signal, is constituted by the divided resonator group. This increases the area occupied by the resonant circuit on the piezoelectric substrate compared to the case where the resonant circuit is formed of a single acoustic wave resonator. As a result, the power consumption per unit area is reduced, and thus the IMD generated by the resonance circuit is reduced. Since the split resonator group constitutes a resonance circuit in which the power of the signal is most likely to be concentrated, the effect of reducing the IMD can be maximized with respect to the disadvantage of the large-sized resonance circuit.

The frequency of the IMD may be a frequency obtained by subtracting the frequency of the 2 nd transmission signal from 2 times the frequency of the 1 st transmission signal.

As an example, when the 1 st transmission signal and the 2 nd transmission signal are transmission signals of Band1 and Band3 in LTE (registered trademark), such a frequency of IMD is repeated with the frequency of the reception Band of Band 1. Therefore, by reducing the IMD at such a frequency, degradation of the reception sensitivity of Band1 can be suppressed.

Further, the 2 nd transmission filter may include: more than one series arm resonant circuit arranged on the 2 nd path; and one or more parallel-arm resonant circuits arranged on a path connecting a corresponding node on the 2 nd path to a ground, wherein at least one of the one or more series-arm resonant circuits of the 2 nd transmission filter and a resonant circuit closest to the common terminal among the one or more parallel-arm resonant circuits is composed of a divided resonator group composed of a plurality of divided resonators connected in series with each other.

With this configuration, the same effect as the IMD reduction effect described for the 1 st transmission filter can be obtained also in the 2 nd transmission filter.

A multiplexer according to an embodiment of the present invention includes: a1 st transmission filter disposed on a1 st path connecting the common terminal and the 1 st terminal; a2 nd transmission filter disposed on a2 nd path connecting the common terminal and the 2 nd terminal; and a reception filter disposed on a3 rd path connecting the common terminal and the 3 rd terminal, the frequency of intermodulation distortion being included in a passband of the reception filter, the intermodulation distortion being generated by a1 st transmission signal whose frequency is included in the passband of the 1 st transmission filter and a2 nd transmission signal whose frequency is included in the passband of the 2 nd transmission filter, the 1 st transmission filter having: more than one series arm resonant circuit arranged on the 1 st path; and one or more parallel-arm resonant circuits disposed on a path connecting a corresponding node on the 1 st path and a ground, wherein each of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 1 st transmission filter is configured of an elastic wave resonator having an IDT electrode, and a duty ratio of an IDT electrode of at least one of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 1 st transmission filter, which is closest to the common terminal, is smaller than a duty ratio of an IDT electrode of any of the other resonant circuits of the 1 st transmission filter.

According to this configuration, in the 1 st transmission filter, at least one of the resonance circuits closest to the common terminal, that is, the IDT electrode of the resonance circuit in which the IMD is likely to occur due to the easy concentration of the power of the signal, has a smaller duty ratio than the IDT electrode of the other resonance circuit. Thus, the repetition period of the electrode fingers of the resonant circuit can be increased as compared with the case where the resonant circuit is constituted by the same duty ratio of the IDT electrode as that of other resonant circuits, and thus the area occupied by the resonant circuit on the piezoelectric substrate becomes large. As a result, the power consumption per unit area is reduced, and thus the IMD generated by the resonance circuit is reduced. Since the duty ratio of the IDT electrode of the resonant circuit, which makes the power of the signal most easily concentrated, is reduced, the effect of reducing the IMD can be maximized against the disadvantage of the larger size of the resonant circuit.

Further, the 2 nd transmission filter may include: more than one series arm resonant circuit arranged on the 2 nd path; and one or more parallel-arm resonant circuits disposed on a path connecting a corresponding node on the 2 nd path and a ground, wherein each of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 2 nd transmission filter is configured of an elastic wave resonator having an IDT electrode, and a duty ratio of an IDT electrode of at least one of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 2 nd transmission filter, which is closest to the common terminal, is smaller than a duty ratio of an IDT electrode of any of the other resonant circuits of the 2 nd transmission filter.

Further, among the 1 st transmission filter and the 2 nd transmission filter, one may have a passband of 1920MHz to 1980MHz, the other may have a passband of 1710MHz to 1785MHz, and the reception filter may have a passband of 2110MHz to 2200 MHz.

According to this configuration, the pass Band of the 1 st filter and the pass Band of the 2 nd filter are one of the transmission Band1Tx of Band1 and the transmission Band3Tx of Band3 and the other. The passband of the reception filter is the reception Band1Rx of Band 1. That is, the 1 st transmission filter and the 2 nd transmission filter are used as one and the other of the transmission filter of Band1 and the transmission filter of Band3, and the reception filter is used as the reception filter of Band 1.

Here, the frequency obtained by subtracting the frequency of the transmission signal of Band3 from 2 times the frequency of the transmission signal of Band1 is repeated with the frequency of the reception signal of Band 1. Therefore, when the transmission signal of Band1 and the transmission signal of Band3 are transmitted simultaneously, the transmission signal of Band1 and the transmission signal of Band3 become interference waves to each other, and a high-level IMD is generated in the reception Band1Rx of Band 1.

Therefore, a filter in which countermeasures for reducing IMD are implemented is used for the 1 st transmission filter or for both the 1 st transmission filter and the 2 nd transmission filter. Thus, IMD generated in the reception Band1Rx of Band1 can be reduced, and degradation of reception sensitivity of Band1 can be suppressed, for example.

The multiplexer according to the embodiment of the present invention has been described above, but the present invention is not limited to the respective embodiments. The present embodiment may be modified variously by those skilled in the art, and the configuration of combining the constituent elements of the different embodiments may be included in the scope of one or more embodiments of the present invention, as long as the gist of the present invention is not impaired.

Industrial applicability

The present invention is widely applicable to communication devices such as mobile phones as a multiplexer having excellent low noise.

Claims

1. A multiplexer is provided with:

a1 st transmission filter disposed on a1 st path connecting the common terminal and the 1 st terminal;

a2 nd transmission filter disposed on a2 nd path connecting the common terminal and the 2 nd terminal; and

a receiving filter disposed on a3 rd path connecting the common terminal and the 3 rd terminal,

the frequency of intermodulation distortion, which is generated by a1 st transmission signal whose frequency is included in the passband of the 1 st transmission filter and a2 nd transmission signal whose frequency is included in the passband of the 2 nd transmission filter,

the 1 st transmission filter has: more than one series arm resonant circuit arranged on the 1 st path; and at least one parallel-arm resonant circuit arranged on a path connecting the corresponding node on the 1 st path to the ground,

the resonance circuit closest to the common terminal among the one or more series-arm resonance circuits and the one or more parallel-arm resonance circuits of the 1 st transmission filter is a1 st series-arm resonance circuit,

the 1 st series-arm resonant circuit and the 1 st parallel-arm resonant circuit connected to the 1 st series-arm resonant circuit are constituted by a divided resonator group constituted by a plurality of divided resonators connected in series to each other.

2. The multiplexer of claim 1 wherein,

the frequency of the intermodulation distortion is a frequency obtained by subtracting the frequency of the 2 nd transmission signal from 2 times the frequency of the 1 st transmission signal.

3. The multiplexer according to claim 1 or 2, wherein,

the 2 nd transmission filter has: more than one series arm resonant circuit arranged on the 2 nd path; and at least one parallel-arm resonant circuit arranged on a path connecting the corresponding node on the 2 nd path to the ground,

at least one of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits of the 2 nd transmission filter, which is closest to the common terminal, is constituted by a divided resonator group constituted by a plurality of divided resonators connected in series with each other.

4. A multiplexer is provided with:

the one or more series-arm resonant circuits of the 1 st transmission filter and the one or more parallel-arm resonant circuits are each constituted by an elastic wave resonator having interdigital transducer IDT electrodes,

the duty ratio of the IDT electrode of the 1 st series-arm resonant circuit and the IDT electrode of the 1 st parallel-arm resonant circuit connected to the 1 st series-arm resonant circuit is smaller than the duty ratio of the IDT electrode of any other resonant circuit of the 1 st transmission filter.

5. The multiplexer of claim 4, wherein,

6. The multiplexer of claim 4 or 5, wherein,

the one or more series-arm resonant circuits of the 2 nd transmission filter and the one or more parallel-arm resonant circuits are each constituted by an elastic wave resonator having IDT electrodes,

the duty ratio of the IDT electrode of at least one of the one or more series-arm resonant circuits and the one or more parallel-arm resonant circuits closest to the common terminal of the 2 nd transmission filter is smaller than the duty ratio of the IDT electrode of any other resonant circuit of the 2 nd transmission filter.

7. The multiplexer of any one of claims 1, 2, 4, 5 wherein,

among the 1 st transmission filter and the 2 nd transmission filter, one has a passband of 1920MHz to 1980MHz, the other has a passband of 1710MHz to 1785MHz,

the passband of the receiving filter is 2110MHz or more and 2200MHz or less.